tabloid-0.3: Component.hs

module Component where

import Data.IORef
import Control.Applicative

-- reference management:
newtype Ref a =  Ref (IORef a)

infixr 0 .<, .<<, .>, .>>

(.>>) :: Ref (state) -> (state -> IO a) -> IO a
(.>>) (Ref c) a = readIORef c >>= a

(.<<) :: Ref (state) -> (state -> IO state) -> IO ()
(.<<) (Ref c) a = readIORef c >>= a >>= writeIORef c

(.<) :: Ref (state) -> (state -> state) -> IO ()
(.<) (Ref c) a = readIORef c >>= writeIORef c . a

(.>) :: Ref (state) -> (state -> a) -> IO a
(.>) c getter =  c .>> return . getter
    
newRef :: state -> IO (Ref (state))
newRef c = Ref <$> newIORef c 

unRef :: Ref (state) -> IO (state)
unRef (Ref c) = readIORef c